How do I add an attachment to emails on yahoo beta?

Go to "Compose", write your email, then go to "Attach" (it has a little picture of a paper clip beside it) then just browse through your documents and attach whatever you want :)

How do I add an attachment to a message? You can add attachments at any time while you're composing an email. Here's how to do it: Click Attach (next to the paperclip) above the Compose window. You’ll recognize your computer’s usual file-locating window, not Yahoo! Mail’s. Find the file you’d like to attach. Click Open or OK. You'll see the file name appear above your Compose window. If you want to add more attachments, repeat this process. You can keep adding attachments until you reach the 10MB limit. But you don't have to! If you decide not to include an attachment, click Remove beside the name of the attached file. Nice work. Look at you—adding attachments! You can send many types of files as attachments, including word processor or spreadsheet documents, audio files, image files (bmp, jpg., gif, etc.), web pages saved as HTML files, and more. You can add multiple attachments up to a sum total of 10MB to any email message. If you'd like to be able to send and receive larger messages with attachments, check out Mail Plus. With Yahoo! Mail Plus, you can send and receive messages up to 20MB in size.

Are you thick?? You click the Paperclip!!